Cored carbon electrode for arc-lamps.



R. R. HERBST. GORED CARBON ELECTRODE FOR ARC LAMPS.

APPLIUATION FILED JAN. 27,1911.

Patented Oct. 29, 1912.

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BORED CARBON ELECTRODE FOR ARC-LAMPS.

Specification of Letters Patent.

racemes Oct. 29,1912.

Application filed Fanuary 27, 1911. Serial 130. 605,072.

citizen of the United States, residing H1 Freeland, 24112613118 county, State of Pennsylvania, have invented certain new and useful Improvements in Cored Carbon Electrodes for Arc-Lamps, of which the following isa specification.

My invention relates to carbon electrodes for are lamps which are provided with a antral core of relatively soft carbon.

in the employment of arc lamps for the ro'ection of shadow pictures u on a screen i 7 it is necessary in order to obtain the best results that the light shall be steady and shall occupy a constant position, and the desire of those who heretofore have suggested the using of cored carbon electrodes has been the roduction of an electrode which would pro uce a steady light. But as far as I am aware, the various constructions of cored electrodes of the character above stated have not been satisfactory. In some of the proposed structures, the are from which the light radiates travels or moves to difierent positions with respect to the transverse area of the carbon, whereas in other proposed forms of constmctionthe softcentral portion of the carbon is permitted to vaporize or disintegrate too ra idly with the result that the end of the car on is left ra ged and with the further result that the intensity and sharpness of the light at the point'where it is most desired is decreased.

The pur ose of my invention is to construct a car on of the character stated which is provided with means for maintaining the electric arc in a constant position with respect to the transverse area of the carbon whereby the light which radiates therefrom is steady and stationary.

The further purpose of my invention is to cause an even disintegration or vaporization of the end of the carbon electrode which is necessary to secure the best results.

In order that my invention may be more readily understood and comprehended, I

have illustrated a convenient form of embodiment I thereof in the accompanying and Fig. 3 is a section on the-line 33 of Fig. 2. 1

Referring to the drawings :--1 designates a cylindrical carbon electrode having a central core :2 of relatively soft carbon and a groove 3 which extends longitudinally of the electrode and the bottom of which is located a short distance from the periphery of the core 2- of relatively soft carbon or other suitable material. The groove 3, as illustrated, is il -shaped but it will be understood that, the shape of the said groove may be varied as desired. The essential feature or characteristic of construction is that the bottom of the said groove shall not extend to the core 2 of relatively soft carbon but shall be located a short distance therefrom. The thickness of the strip 4 of relatively hard carbon between the bottom of the roove 3 and-"the core Zgnay be varied as desired and as may be necessary, although I have obtained good results with carbons in which such strips were approximately three sixteenths of an inch in thickness. It has been found. that when the bottom of the groove is located a short distance from the core of soft carbon 2 the electric arc is maintained at a constant position with respect to the transverse area of the electrode 1. It has been found also that disintegration or vaporization of the soft core of the carbon takes place less rapidly in proportion to the disintegration or vaporization of the sur-' 1 if the groove 3 extended entirely to the core 2. If the carbon electrode were not provided with a groove the electric arc would move from one position to another with respect to the core/2 and in consequence the light would be unsteady and undesirable.

Having thus described my invention, I

l claim 1. Acarbon electrode for arc lamps having a core of relatively soft carbon'and a groove or opening extending longitudinally of said carbon and also having a narrow strip of the relatively hard carbon located between the bottom of the said groove or opening and the said core. Y

fl igoeeeee 2. A carbon electrode for are lamps. liev- In testimony that I claim the foregoing as 111;; a core of relatively soft material and my invention, I have hereunto signed my 10 also having a groove extending longitudiname this 24th day of January, A. D1911.

nelly of said carbon the bottonfof-whiohw I groove is loeetecl a distance from said core ROGER HERBST' so as to leave a strip of relatively hard cer- In the presence of' bon between the bottom of said groove and Geo. H. WEIDNER,

seil core, CARRIE E. KLEINFELDER.

flop'ies of this .petent may be obtained for five cents each, by addressing" the Commissionea: of Patents,

Washington, D. U. 

